Image capturing apparatus, light emitting apparatus, and control methods thereof

ABSTRACT

An image capturing apparatus that controls a light emitting apparatus, performs communication with the light emitting apparatus at predetermined intervals, decides information regarding a period of time remaining before the light emitting apparatus emits light, based on the remaining time to exposure and a period of time from when the remaining time starts decreasing, to when the wireless communication unit performs a first wireless communication thereafter, and performs control so that the information regarding the decided period of time is transmitted to the light emitting apparatus through the first wireless communication with the light emitting apparatus. In a case where transmission and reception of the information regarding the period of time between the image capturing apparatus and the light emitting apparatus fail, the image capturing apparatus performs control so that the information regarding the period of time is re-transmitted.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an image capturing apparatus, a lightemitting apparatus, and control methods thereof, particularly relates toa technique that is employed by an image capturing apparatus to control,via wireless communication, light emission that is performed by a lightemitting apparatus.

Description of the Related Art

In a system in which an image capturing apparatus such as a camera, anda light emitting apparatus such as a flash, are connected to each othervia wireless communication, synchronization between exposure performedby the camera and light emission performed by the flash is establishedby the camera, transmitting light emission information, which containsinformation regarding the timing of light emission performed by theflash, to the flash (Japanese Patent Laid-Open No. 2010-185961, JapanesePatent Laid-Open No. 2016-021020, and Japanese Patent Laid-Open No.2011-242513).

Also, Japanese Patent Laid-Open No. 2010-185958 discloses that, after acamera transmits a light-emission command, a flash transmits a responsepacket to the camera, and the flash emits light upon a predeterminedperiod of time elapsing. In this case, if the camera does not receive aresponse packet from the flash within a predetermined period of time, itis determined that the camera has failed to transmit the light-emissioncommand, but the camera transitions to a shooting operation withoutperforming re-transmission processing.

Thus, in Japanese Patent Laid-Open No. 2010-185958, the camera does notperform re-transmission processing when the camera has failed totransmit the transmission of a light-emission command to the flash.Therefore, synchronization between exposure performed by the camera andlight emission performed by the flash cannot be established.

SUMMARY OF THE INVENTION

The present invention has been made in consideration of theaforementioned problems, and realizes, even when necessary informationis not transmitted and received between an image capturing apparatus anda light emitting apparatus, a technique for establishing synchronizationbetween the timing of exposure performed by the image capturingapparatus and the timing of light emission performed by the lightemitting apparatus in cases where a wireless communication schemethrough which communication is performed at predetermined intervals isemployed.

In order to solve the aforementioned problems, the present inventionprovides an image capturing apparatus that controls a light emittingapparatus, comprising: a wireless communication unit configured toperform communication with the light emitting apparatus at predeterminedintervals; a deciding unit configured to, upon receiving an instructionto cause the light emitting apparatus to emit light to perform shooting,decide information regarding a period of time remaining before the lightemitting apparatus emits light, based on the remaining time to exposureand a period of time from when the remaining time starts decreasing, towhen the wireless communication unit performs a first wirelesscommunication thereafter; and a control unit configured to performcontrol so that the information regarding the period of time decided bythe deciding unit is transmitted to the light emitting apparatus throughthe first wireless communication with the light emitting apparatus,wherein, in a case where transmission and reception of the informationregarding the period of time between the image capturing apparatus andthe light emitting apparatus fail, the control unit performs control sothat the information regarding the period of time is re-transmitted.

In order to solve the aforementioned problems, the present inventionprovides a light emitting apparatus that is controlled by an imagecapturing apparatus, comprising: a wireless communication unitconfigured to perform communication with the image capturing apparatusat predetermined intervals; and a deciding unit configured to, afterreceiving light emission information that is used to perform lightemission preparations from the image capturing apparatus, receive timeinformation regarding a period of time from when remaining time beforethe image capturing apparatus performs exposure starts decreasing, towhen the wireless communication unit performs a first wirelesscommunication thereafter, and obtain a period of waiting time remainingbefore the light emitting apparatus emits light, based on theinformation regarding the period of time, wherein, in a case where thedeciding unit receives new time information after receiving the timeinformation from the image capturing apparatus, the deciding unitcancels the period of waiting time decided based on the previouslyreceived time information, and decides a period of waiting time based onthe newly received time information.

In order to solve the aforementioned problems, the present inventionprovides a method for controlling an image capturing apparatus thatincludes a wireless communication unit configured to communicate with alight emitting apparatus at predetermined intervals, and controls thelight emitting apparatus via wireless communication, the methodcomprising: upon receiving an instruction to cause the light emittingapparatus to emit light to perform shooting, deciding time informationregarding a period of time remaining before the light emitting apparatusemits light, based on the remaining time to exposure and a period oftime from when the remaining time starts decreasing to when the imagecapturing apparatus performs the first wireless communicationthereafter; and controlling such that the time information regarding thedecided period of time is transmitted to the light emitting apparatusthrough the first wireless communication with the light emittingapparatus, wherein, in the controlling, in a case where transmission andreception of the time information between the image capturing apparatusand the light emitting apparatus fail, the control unit performs controlso that the time information is re-transmitted.

In order to solve the aforementioned problems, the present inventionprovides a method for controlling a light emitting apparatus thatincludes a wireless communication unit configured to communicate with animage capturing apparatus at predetermined intervals, and is controlledby the image capturing apparatus via wireless communication, the methodcomprising: after receiving light emission information that is used toperform light emission preparations from the image capturing apparatus,receiving time information regarding a period of time from whenremaining time before the image capturing apparatus performs exposurestarts decreasing, to when the first wireless communication thereafteris to be performed, and obtaining a period of waiting time remainingbefore the light emitting apparatus emits light, based on theinformation regarding the period of time, wherein, in the obtaining, ina case where new time information is received after the time informationhas been received from the image capturing apparatus, the period ofwaiting time decided based on the previously received time informationis cancelled, and a period of waiting time is decided based on the newlyreceived time information.

In order to solve the aforementioned problems, the present inventionprovides a non-transitory computer-readable storage medium storing aprogram for causing a computer to execute a method for controlling animage capturing apparatus that includes a wireless communication unitconfigured to communicate with a light emitting apparatus atpredetermined intervals, and controls the light emitting apparatus viawireless communication, the method comprising: upon receiving aninstruction to cause the light emitting apparatus to emit light toperform shooting, deciding time information regarding a period of timeremaining before the light emitting apparatus emits light, based on theremaining time to exposure and a period of time from when the remainingtime starts decreasing to when the image capturing apparatus performsthe first wireless communication thereafter; and controlling such thatthe time information regarding the decided period of time is transmittedto the light emitting apparatus through the first wireless communicationwith the light emitting apparatus, wherein, in the controlling, in acase where transmission and reception of the time information betweenthe image capturing apparatus and the light emitting apparatus fail, thecontrol unit performs control so that the time information isre-transmitted.

In order to solve the aforementioned problems, the present inventionprovides a non-transitory computer-readable storage medium storing aprogram for causing a computer to execute a method for controlling alight emitting apparatus that includes a wireless communication unitconfigured to communicate with an image capturing apparatus atpredetermined intervals, and is controlled by the image capturingapparatus via wireless communication, the method comprising: afterreceiving light emission information that is used to perform lightemission preparations from the image capturing apparatus, receiving timeinformation regarding a period of time from when remaining time beforethe image capturing apparatus performs exposure starts decreasing, towhen the first wireless communication thereafter is to be performed, andobtaining a period of waiting time remaining before the light emittingapparatus emits light, based on the information regarding the period oftime, wherein, in the obtaining, in a case where new time information isreceived after the time information has been received from the imagecapturing apparatus, the period of waiting time decided based on thepreviously received time information is cancelled, and a period ofwaiting time is decided based on the newly received time information.

According to the present invention, it is possible to, even whennecessary information is not transmitted and received between an imagecapturing apparatus and a light emitting apparatus, establishsynchronization between the timing of exposure performed by the imagecapturing apparatus and the timing of light emission performed by thelight emitting apparatus in cases where a wireless communication schemethrough which communication is performed at predetermined intervals isemployed.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing an example of a flash synchronizationshooting system according to a first embodiment.

FIG. 2A is a block diagram showing an example of a configuration of acamera body according to the first embodiment.

FIG. 2B is a block diagram showing an example of a configuration of aflash according to the first embodiment.

FIG. 3 is a sequence diagram illustrating operations performed duringflash synchronization shooting according to the first embodiment.

FIG. 4 is a sequence diagram illustrating operations performed duringflash synchronization shooting according to a second embodiment.

FIG. 5 is a sequence diagram illustrating operations performed duringflash synchronization shooting according to a third embodiment.

FIG. 6 is a sequence diagram illustrating operations performed duringflash synchronization shooting according to a fourth embodiment.

FIG. 7A is a diagram showing an example of a flash synchronizationshooting system according to a fifth embodiment.

FIG. 7B is a diagram showing a configuration of a transmitter accordingto the fifth embodiment.

FIGS. 8A and 8B are sequence diagrams illustrating operations performedduring flash synchronization shooting according to the fifth embodiment.

FIG. 9 is a diagram showing an example of a flash synchronizationshooting system according to a sixth embodiment.

FIGS. 10A and 10B are sequence diagrams illustrating operationsperformed during flash synchronization shooting according to the sixthembodiment.

FIG. 11 is a sequence diagram illustrating operations performed duringflash synchronization shooting according to the sixth embodiment.

FIG. 12 is a sequence diagram illustrating operations performed duringflash synchronization shooting according to the sixth embodiment.

FIGS. 13A and 13B are sequence diagrams illustrating operationsperformed during flash synchronization shooting according to a seventhembodiment.

FIGS. 14A and 14B are sequence diagrams illustrating operationsperformed during flash synchronization shooting according to an eighthembodiment.

FIGS. 15A and 15B are sequence diagrams illustrating operationsperformed during flash synchronization shooting according to a ninthembodiment.

FIGS. 16A and 16B are sequence diagrams illustrating operationsperformed during flash synchronization shooting according to a tenthembodiment.

FIGS. 17 and 18 are sequence diagrams illustrating operations performedduring flash synchronization shooting according to an eleventhembodiment.

FIG. 19 is a sequence diagram illustrating operations performed duringflash synchronization shooting according to a twelfth embodiment.

FIGS. 20A and 20B are sequence diagrams illustrating operationsperformed during flash synchronization shooting according to athirteenth embodiment.

DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention will be described in detail below.The following embodiments are merely examples for practicing the presentinvention. The embodiments should be properly modified or changeddepending on various conditions and the structure of an apparatus towhich the present invention is applied. The present invention should notbe limited to the following embodiments. Also, parts of the embodimentsto be described later may be properly combined.

First Embodiment

The following describes a flash synchronization shooting systemaccording to a first embodiment.

FIG. 1 is a diagram showing an example of a flash synchronizationshooting system according to the present embodiment. The flashsynchronization shooting system according to the present embodiment isapplicable to shooting that involves a flash that performs wirelesscommunication with a digital camera or a film camera. A camera 10, whichis an image capturing apparatus, controls a flash 300, which is a lightemitting apparatus, via wireless communication. The wirelesscommunication scheme employed herein is a short-range wirelesscommunication scheme such as Bluetooth (registered trademark). Thecamera 10 is a digital single-lens reflex camera, for example. Thepresent embodiment is applicable to shooting that involves a flash thatperforms wireless communication with a camera, which is not limited to adigital camera, but may be a film camera. A wireless communication unit111 is built into the camera 10. A wireless communication unit 308 isbuilt into the flash 300. When the camera 10 and the flash 300 are setto a wireless communication mode, the camera 10 operates as a master andthe flash 300 operates as a slave, and thus the camera 10 and the flash300 can transmit/receive data to/from each other via the wirelesscommunication units 111 and 308.

FIG. 2A is a block diagram showing a configuration of the camera 10according to the present embodiment. The camera 10 according to thepresent embodiment includes a camera body 100 and a lens unit 200.

First, the following describes the configuration and the functions ofthe camera body 100.

In the camera body 100, a microcomputer (hereinafter referred to as a“camera microcomputer”) 101 executes control programs such as firmwareto control operations of each of the components included in the camerabody 100.

The camera microcomputer 101 includes, for example, a CPU, a ROM, a RAM,an input/output control circuit (an I/O control circuit), a multiplexer,a timer circuit, an EEPROM, an A/D converter, and a D/A converter, andis configured as a single IC chip with a built-in microcomputer.

An image sensor 102 includes an image capturing device such as a CCD ora CMOS, which includes an infrared cut filter and a low pass filter, anda lens group 202 forms an optical image of a subject during a shootingoperation.

A shutter 103 is closed during a shooting preparation operation, toblock light from entering the image sensor 102, and is open during ashooting operation, to guide a light ray to the image sensor 102.

A main mirror (semitransparent mirror) 104 reflects off incident lightfrom the lens group 202 during the shooting preparation operation, andforms an image on a focusing screen 105.

An image of the subject is formed on the focusing screen 105 due to alight ray reflected off the main mirror 104. A photometric unit 106includes an image forming lens and a photometric sensor. A shooting areaof the subject is divided into a plurality of areas, and the photometricsensor performs light metering for each of the areas. The photometricsensor detects the amount of light received from the subject imageformed on the focusing screen 105, via a pentaprism 108.

A focus detection unit 107 functions as a focus detection opticalsystem. The focus detection unit 107 includes a secondary image formingmirror, a secondary image forming lens, a focus detection sensor, and soon. The focus detection sensor has a plurality of focus detection areas,and the focus detection areas are respectively included in thedivisional areas of the photometric sensor.

Note that the camera body 100 has a recording medium such as a memorycard or a hard disk (not shown), which is used to record capturedimages, and is built into, or is detachable from, the camera body 100.

The pentaprism 108 guides the subject image formed on the focusingscreen 105 to the photometric sensor of the photometric unit 106, and toan optical viewfinder 110.

A sub mirror 109 guides a light ray that has entered from the lens group202 and has passed through the main mirror 104, to the focus detectionsensor of the focus detection unit 107.

The optical viewfinder 110 allows a photographer looking into theoptical viewfinder 110 to visually check the focus state of the subjectimage.

The wireless communication unit 111 performs predetermined wirelesscommunication with camera accessories such as a flash and a remotecontrol, which are external apparatuses. It is envisaged that thewireless communication unit 111 is a wireless module, a functional unitprovided in the camera microcomputer 101, or the like. In the presentembodiment, the wireless communication unit 111 is a wireless module.The camera-side wireless module 111 is provided with an antenna forwireless communication, and realizes short-range wireless communicationconforming to the IEEE 802.15 standard (Bluetooth (registeredtrademark)). The camera-side wireless module 111 performs wirelesscommunication with an external apparatus such as a flash or a remotecontrol at predetermined intervals, and notifies the cameramicrocomputer 101 of the points in time at which the camera-sidewireless module 111 received null data or non-null data.

The camera body 100) also includes a camera-side interface (IF) 112, andtransmits/receives data to/from the camera microcomputer 101 via thecamera-side interface 112.

Upon an external apparatus such as the flash 300 or a transmitter 400described below being attached to an accessory shoe (not shown) of thecamera body 100, the camera-side interface 112 is connected to aflash-side interface 309 of the flash 300 or a transmitter-sideinterface 403 of the transmitter 400. As a result, the cameramicrocomputer 101 can communicate with a flash microcomputer 301 or atransmitter microcomputer 401.

Next, the following describes the configuration and functions of thelens unit 20).

In the lens unit 200, a microcomputer (hereinafter referred to as a“lens microcomputer”) 201 executes control programs such as firmware tocontrol operations of each of the components included in the lens unit200.

The lens microcomputer 201 includes, for example, a CPU, a ROM, a RAM,an input/output control circuit (an I/O control circuit), a multiplexer,a timer circuit, an EEPROM, an A/D converter, and a D/A converter, andis configured as a single IC chip with a built-in microcomputer.

The lens group 202 includes a plurality of lenses such as a zoom lensand a focus lens.

A lens drive unit 203 moves an optical system for adjusting a focalposition of the lens group 202.

The lens microcomputer 201 controls a diaphragm 204, using a diaphragmcontrol unit 205.

Note that the focal point distance of the lens group 202 may be a singlefocal point distance, or variable like that of a zoom lens.

Next, the following describes the configuration and functions of theflash 300 with reference to FIG. 2B.

In the flash 300, the microcomputer (hereinafter referred to as the“flash microcomputer”) 301 executes control programs such as firmware tocontrol operations of each of the components included in the flash 300.

The flash microcomputer 301 includes, for example, a CPU, a ROM, a RAM,an input/output control circuit (an I/O control circuit), a multiplexer,a timer circuit, an EEPROM, an A/D converter, and a D/A converter, andis configured as a single IC chip with a built-in microcomputer.

A light emitting unit 302 is a xenon tube, for example, and emits lightupon a pulse voltage of several kilovolts being applied from a triggercircuit 303 to a main capacitor (not shown) and xenon being excited byenergy that has been charged in the main capacitor, and irradiates thesubject with the light.

The trigger circuit 303 receives a trigger signal pulse output from theflash microcomputer 301 at the time of light emission.

A light emission control unit 304 controls the start and end of lightemission performed by the light emitting unit 302, in conjunction withthe trigger circuit 303.

A light receiving device 305 is a photodiode or the like that receivesan amount of light from the light emitting unit 302, and receives lightfrom the light emitting unit 302 directly or via an optical fiber (notshown).

A reflector 306 and a Fresnel lens 307 each efficiently collect lightfrom the light emitting unit 302 toward the subject.

The wireless communication unit 308 performs wireless communication withthe camera body 100. It is envisaged that the wireless communicationunit 308 is a wireless module, a functional unit provided in the flashmicrocomputer 301, or the like. In the present embodiment, the wirelesscommunication unit 308 is a wireless module. The flash-side wirelessmodule 308 is provided with an antenna for wireless communication, andrealizes short-range wireless communication conforming to the IEEE802.15 standard (Bluetooth (registered trademark)). The flash-sidewireless module 308 performs wireless communication with the camera body100 at predetermined intervals, and notifies the flash microcomputer 301of the points in time at which the flash-side wireless module 308received null data or non-null data.

The flash 300 includes the flash-side interface 309, andtransmits/receives data to/from the flash microcomputer 301 via theflash-side interface 309. Note that when the flash 300 is attached tothe accessory shoe (not shown) of the camera body 100, the flash 300operates as a master, and performs wireless communication with otherflashes that operate as slaves.

Upon the flash 300 being attached to the accessory shoe (not shown) ofthe camera body 100, the flash-side interface 309 is connected to thecamera-side interface 112 of the camera body 100. As a result, the flashmicrocomputer 301 can communicate with the camera microcomputer 101.

Next, with reference to FIG. 3, the following describes an operationsequence of flash synchronization shooting in a case where the camerabody 100 and the flash 300 perform one-to-one communication as shown inFIG. 1.

In step S100, the camera-side wireless module 111 and the flash-sidewireless module 308 perform wireless communication at predeterminedintervals (intervals a) asynchronously with the camera microcomputer 101or the flash microcomputer 301. If there is no data to be transmitted,the camera-side wireless module 111 and the flash-side wireless module308 transmit/receive null data to/from each other. The camera-sidewireless module 111 and the flash-side wireless module 308 respectivelynotify the camera microcomputer 101 and flash microcomputer 301 of thepoints in time at which the camera-side wireless module 111 and theflash-side wireless module 308 received non-null data.

Upon the camera 10 being powered ON, if the flash has been set to theflash shooting mode, the camera microcomputer 101 controls and sets thecamera-side wireless module 111 so that the camera-side wireless module111 can receive terminal information regarding the flash 300, which is acommunication partner. Upon the flash 300 being powered ON, the flashmicrocomputer 301 controls the flash-side wireless module 308 to set awireless frequency channel that is to be used, and transmits terminalinformation regarding the flash 300.

Upon receiving terminal information regarding the flash 300, the camera10 issues a connection request to the flash 300, and then the camera 10and the flash 300 transmit/receive apparatus information and the liketo/from each other. As a result, the camera 10 and the flash 300 cancommunicate with each other at the predetermined communication intervalsa. After the camera 10 and the flash 300 have become able to communicatewith each other in this way, the camera microcomputer 101 enters a statein which the camera microcomputer 101 waits for a shutter releaseoperation that is performed by the photographer (a shooting standbystate).

Upon a shutter button (not shown) being pressed halfway down (a shootingpreparation instruction), the camera microcomputer 101 generates a firstsignal SW1. Upon receiving the first signal SW1, the cameramicrocomputer 101 starts shooting preparation operations to perform AF(Automatic Focus) processing, AE (Automatic Exposure) processing, AWB(Automatic White Balance) processing, EF (pre-flash emission)processing, and so on. Upon the shutter button being fully pressed down(a shooting instruction), the camera microcomputer 101 generates asecond signal SW2. Upon receiving the second signal SW2, the cameramicrocomputer 101 starts a series of shooting operations that start withreading of image signals out of the image sensor 102 and end withwriting of image data to a recording medium.

Upon the second signal SW2 being turned ON in step S101, the cameramicrocomputer 101 outputs, in step S102, light emission information,which contains, for example, information regarding the amount of lightto be emitted and the light emission mode of the flash 300, to thecamera-side wireless module 111.

In step S103, upon the time to start wireless communication beingreached, the camera-side wireless module 111 transmits light emissioninformation to the flash-side wireless module 308. In this case,wireless communication between the camera-side wireless module 111 andthe flash-side wireless module 308 does not synchronize with the cameramicrocomputer 101 or the flash microcomputer 301. Therefore, the timingat which the camera microcomputer 101 output light emission informationto the camera-side wireless module 111 in step S102 does not necessarilycoincide with the timing at which the camera-side wireless module 111transmitted light emission information to the flash-side wireless module308 in step S103.

In step S104, the flash-side wireless module 308 outputs the lightemission information received from the camera-side wireless module 111to the flash microcomputer 301.

In step S105, the flash microcomputer 301 outputs a response to thelight emission information to the flash-side wireless module 308, and instep S106, the flash microcomputer 301 starts light emission preparationoperations based on the light emission information.

In step S107, upon the time to start wireless communication beingreached, the flash-side wireless module 308 transmits a response to thecamera-side wireless module 111.

In step S108, the camera-side wireless module 111 notifies the cameramicrocomputer 101 of the timing at which the camera-side wireless module111 received the response from the flash-side wireless module 308.

In step S109, after receiving the response notification from thecamera-side wireless module 111, the camera microcomputer 101 starts atimer of the camera microcomputer 101.

In step S110, the camera microcomputer 101 performs control such asdiaphragm driving control and mirror lifting up control. Upon completionof processing for control such as diaphragm driving control and mirrorlifting up control, which varies depending on shooting conditions, theremaining time to exposure is set to t0.

Upon the remaining time t0 to exposure being determined, the cameramicrocomputer 101 stops the timer in step S111, and acquires a timervalue (a period of time) β in step S112.

In step S113, the camera microcomputer 101 divides the period of time βacquired in step S112 by the predetermined communication interval α, andthe quotient thus obtained is the number of times wireless communicationwas performed during the period of time β, and the remainder is theperiod of time from when the last wireless communication was performedto when the timer was stopped. If this remainder is expressed as t1, t1is the period of time from when the wireless communication immediatelybefore t0 was determined in step S111 was performed, to when t0 wasdetermined.

In step S114, the camera microcomputer 101 subtracts t1, obtained instep S111, from the predetermined communication interval α, to obtain aperiod of time t2, which is a period of time from when t0 was determinedto when the subsequent wireless communication is to be performed.

In step S115, the camera microcomputer 101 subtracts t2, obtained instep S114, from the remaining time t0 to exposure, determined in stepS110, to obtain a period of time t3, which is a period of time from whenthe first wireless communication after t0 was determined is to beperformed, to when exposure (light emission) is to be performed.

In step S116, the camera microcomputer 101 outputs information regardingthe period of time t3, calculated in step S115, to the camera-sidewireless module 111.

In step S117, upon the time to perform wireless communication beingreached, the camera-side wireless module 111 transmits informationregarding the period of time t3 to the flash-side wireless module 308.

In step S118, the flash-side wireless module 308 outputs informationregarding the period of time t3, received from the camera-side wirelessmodule 111, to the flash microcomputer 301 as light emissioninformation.

In step S119, the flash microcomputer 301 sets t3, received from theflash-side wireless module 308, as the period of waiting time, and uponthe period of time t3 elapsing, the flash microcomputer 301 performslight emission based on information regarding the light emissionpreparations performed in step S106.

In step S120, the camera microcomputer 101 performs exposure upon theperiod of time t0, i.e. t2+t3, elapsing after step S111 has beencompleted. As a result, the camera 10 and the flash 300 synchronize witheach other.

Upon the shooting sequence being complete in this way, the cameramicrocomputer 101 and the flash microcomputer 301 return to the shootingstandby state.

As described above, the camera microcomputer 101 is notified by thecamera-side wireless module 111 of the timing at which light emissioninformation was received (step S108). Thus, the camera microcomputer 101can find out the timing of performing wireless communication with theflash 300, and decide information regarding the period of time t3, whichis a period of time from when the wireless communication is performed towhen the flash 300 emits light. As a result, even in a case where thecamera 10 and the flash 300 perform asynchronous wireless communication,it is possible to establish synchronization between the timing ofexposure performed by the camera 10 and the timing of light emissionperformed by the flash 300.

Note that even in a case where light metering and pre-flash emission arerespectively performed by the camera 10 and the flash 300 after thesecond signal SW2 has been turned ON in step S101, it is possible toestablish synchronization between light metering performed by the camera10 and pre-flash emission performed by the flash 300, in the same manneras in the case of exposure performed by the camera 10 and light emissionperformed by the flash 300.

Second Embodiment

The following describes a flash synchronization shooting systemaccording to a second embodiment.

FIG. 4 is a diagram illustrating an operation sequence of flashsynchronization shooting in a case where the camera 10 and the flash 300perform one-to-one communication as shown in FIG. 1.

The camera-side wireless module 111 according to the second embodimentnotifies the camera microcomputer 101 of the points in time at which thecamera-side wireless module 111 transmitted non-null data. Similarly,the flash-side wireless module 308 notifies the flash microcomputer 301of the points in time at which the flash-side wireless module 308received non-null data.

Note that the configurations of the camera 10 and the flash 300 are thesame as the configurations of those shown in FIGS. 2A and 2B accordingto the first embodiment. Also, the wireless communication schemeemployed by the camera-side wireless module 111 and the flash-sidewireless module 308, and the operations of the camera body 100 performeduntil the second signal SW2 is turned ON are the same as those accordingto the first embodiment.

Upon the second signal SW2 being turned ON in step S201, the cameramicrocomputer 101 outputs, in step S202, light emission information,which contains, for example, information regarding the amount of lightto be emitted and the light emission mode of the flash 300, to thecamera-side wireless module 111.

In step S203, upon the time to start wireless communication beingreached, the camera-side wireless module 111 transmits light emissioninformation to the flash-side wireless module 308. In step S204, thecamera-side wireless module 111 outputs a transmission notification tothe camera microcomputer 101. In this case, wireless communicationbetween the camera-side wireless module 111 and the flash-side wirelessmodule 308 does not synchronize with the camera microcomputer 101 or theflash microcomputer 301. Therefore, the timing at which the cameramicrocomputer 101 output light emission information to the camera-sidewireless module 111 in step S202 does not necessarily coincide with thetiming at which the camera-side wireless module 111 transmitted lightemission information to the flash-side wireless module 308 in step S203.

In step S205, the flash-side wireless module 308 outputs the lightemission information received from the camera-side wireless module 111to the flash microcomputer 301.

In step S206, the flash microcomputer 301 starts light emissionpreparation operations based on the light emission information.

In step S207, after receiving the transmission notification from thecamera-side wireless module 111, the camera microcomputer 101 starts thetimer of the camera microcomputer 101.

Steps S208 to S218 are the same as steps S110 to S120 in FIG. 3according to the first embodiment, and therefore descriptions thereofare omitted.

Upon the shooting sequence being complete in this way, the cameramicrocomputer 101 and the flash microcomputer 301 return to the shootingstandby state.

As described above, the camera microcomputer 101 is notified by thecamera-side wireless module 111 of the timing at which light emissioninformation was transmitted (step S204). Thus, the camera microcomputer101 can find out the timing of performing wireless communication withthe flash 300, and decide information regarding the period of time t3,which is a period of time from when the wireless communication isperformed to when the flash 300 emits light. As a result, even in a casewhere the camera 10 and the flash 300 perform asynchronous wirelesscommunication, it is possible to establish synchronization between thetiming of exposure performed by the camera 10 and the timing of lightemission performed by the flash 300.

Note that even in a case where light metering and pre-flash emission arerespectively performed by the camera 10 and the flash 300 after thesecond signal SW2 has been turned ON in step S201, it is possible toestablish synchronization between light metering performed by the camera10 and pre-flash emission performed by the flash 300, in the same manneras in the case of exposure performed by the camera 10 and light emissionperformed by the flash 300.

Third Embodiment

The following describes a flash synchronization shooting systemaccording to a third embodiment.

FIG. 5 is a diagram illustrating an operation sequence of flashsynchronization shooting in a case where the camera 10 and the flash 300perform one-to-one communication as shown in FIG. 1.

The camera-side wireless module 111 according to the third embodimentnotifies the camera microcomputer 101 of the points in time at which thecamera-side wireless module 111 transmitted data, which may be nulldata. Similarly, the flash-side wireless module 308 notifies the flashmicrocomputer 301 of the points in time at which the flash-side wirelessmodule 308 received data, which may be null data. The configurations ofthe camera 10 and the flash 300 are the same as the configurations ofthose shown in FIGS. 2A and 2B according to the first embodiment. Also,the wireless communication scheme employed by the camera-side wirelessmodule 111 and the flash-side wireless module 308, and the operations ofthe camera body 100 performed until the second signal SW2 is turned ONare the same as those according to the first embodiment.

Also, steps S301 to S307 are the same as steps S201 to S207 according tothe second embodiment, and therefore descriptions thereof are omitted.

In step S308, the camera microcomputer 101 resets and starts the timerevery time the camera microcomputer 101 receives a communicationnotification from the camera-side wireless module 111.

After determining the remaining time t0 to exposure in step S309, thecamera microcomputer 101 stops the timer in step S310 and acquires thevalue of the timer. Then, in step S311, the camera microcomputer 101sets the timer value to t1, which is the period of time from when thewireless communication was performed immediately before the remainingtime t0 to exposure was determined, to when the remaining time t0 toexposure was determined.

Steps S312 to S318 are the same as steps S114 to S120 in FIG. 3according to the first embodiment, and therefore descriptions thereofare omitted.

Upon the shooting sequence being complete in this way, the cameramicrocomputer 101 and the flash microcomputer 301 return to the shootingstandby state.

As described above, the camera microcomputer 101 is notified by thecamera-side wireless module 111 of the timing of performing wirelesscommunication (step S304). Thus, the camera microcomputer 101 can findout the timing of performing wireless communication with the flash 300,and decide information regarding the period of time t3, which is aperiod of time from when the wireless communication is performed to whenthe flash 300 emits light. As a result, even in a case where the camera10 and the flash 300 perform asynchronous wireless communication, it ispossible to establish synchronization between exposure performed by thecamera 10 and light emission performed by the flash 300.

Note that even in a case where light metering and pre-flash emission arerespectively performed by the camera 10 and the flash 300 after thesecond signal SW2 has been turned ON in step S301, it is possible toestablish synchronization between light metering performed by the camera10 and pre-flash emission performed by the flash 300, in the same manneras in the case of exposure performed by the camera 10 and light emissionperformed by the flash 300.

Fourth Embodiment

The following describes a flash synchronization shooting systemaccording to a fourth embodiment.

FIG. 6 is a diagram illustrating an operation sequence of flashsynchronization shooting in a case where the camera 10 and the flash 300perform one-to-one communication as shown in FIG. 1.

In the present embodiment, the camera 10 transmits, to the flash 300,information that is required to calculate the period of time remainingbefore the flash 300 emits light, and the flash 300 calculates theperiod of time t3, which is a period of time from when the flash 300performs wireless communication to when the flash 300 emits light.

Note that, in the fourth embodiment, the configurations of the camera 10and the flash 300, the wireless communication scheme employed by thecamera-side wireless module 111 and the flash-side wireless module 308,and the operations of the camera body 100 performed until the secondsignal SW2 is turned ON are the same as those shown in FIGS. 2A, 2B, and3 according to the first embodiment.

Also, steps S401 to S414 are the same as steps S101 to S114 in FIG. 3according to the first embodiment, and therefore descriptions thereofare omitted.

In step S415, the camera microcomputer 101 transmits, to the camera-sidewireless module 111, the remaining time t0 to exposure determined instep S410 and t2 obtained in step S413.

In step S416, upon the time to start wireless communication beingreached, the camera-side wireless module 111 transmits t0 and t2 to theflash-side wireless module 308.

In step S417, the flash-side wireless module 308 outputs t0 and t2received from the camera-side wireless module 111, to the flashmicrocomputer 301.

In step S418, the flash microcomputer 301 calculates the period of timet3 remaining before light emission, by subtracting t0 from t2.

In step S419, the flash microcomputer 301 sets t3, received from theflash-side wireless module 308, as the period of waiting time, and uponthe period of time t3 elapsing, the flash microcomputer 301 performslight emission based on information regarding the light emissionpreparations performed in step S406.

In step S420, the camera microcomputer 101 performs exposure upon theperiod of time t0, i.e. t2+t3, elapsing after step S411 has beencompleted. As a result, the camera 10 and flash 300 synchronize witheach other.

Upon the shooting sequence being complete in this way, the cameramicrocomputer 101 and the flash microcomputer 301 return to the shootingstandby state.

As described above, the camera microcomputer 101 transmits, to the flash300, information that is required to calculate the period of timeremaining before the flash 300 emits light, and thus the flashmicrocomputer 301 can decide information regarding the period of timet3, which is a period of time from when the wireless communication isperformed to when the flash 300 emits light. As a result, even in a casewhere the camera 10 and the flash 300 perform asynchronous wirelesscommunication, it is possible to establish synchronization between thetiming of exposure performed by the camera 10 and the timing of lightemission performed by the flash 300.

Note that even in a case where light metering and pre-flash emission arerespectively performed by the camera 10 and the flash 300 after thesecond signal SW2 has been turned ON in step S401, it is possible toestablish synchronization between light metering performed by the camera10 and pre-flash emission performed by the flash 300, in the same manneras in the case of exposure performed by the camera 10 and light emissionperformed by the flash 300.

Fifth Embodiment

The following describes a flash synchronization shooting systemaccording to a fifth embodiment.

FIG. 7A is a diagram showing an example of a flash synchronizationshooting system according to the fifth embodiment. The transmitter 400is attached to the accessory shoe (not shown) of the camera body 100.The transmitter 400 includes a wireless communication unit 402. Theconfiguration of the flash 300 is the same as that shown in FIG. 2Baccording to the first embodiment.

When the transmitter 400 and the flash 300 are set to a wirelesscommunication mode, the transmitter 400 operates as a master and theflash 300 operates as a slave, and thus the wireless communication unit402 and the flash-side wireless module 308 perform wirelesscommunication. Note that a master flash (not shown) may be used insteadof the transmitter 400 to perform wireless communication with the slaveflash 300.

Next, the following describes the configuration and functions of thetransmitter 400 with reference to FIG. 7B.

In the transmitter 400, a microcomputer (hereinafter referred to as a“transmitter microcomputer”) 401 executes control programs such asfirmware to control operations of each of the components included in thetransmitter 400.

The transmitter microcomputer 401 includes, for example, a CPU, a ROM, aRAM, an input/output control circuit (an I/O control circuit), amultiplexer, a timer circuit, an EEPROM, an A/D converter, and a D/Aconverter, and is configured as a single IC chip with a built-inmicrocomputer.

The wireless communication unit 402 performs wireless communication withthe flash 300. It is envisaged that the wireless communication unit 402is a functional unit provided in the transmitter 400, or the like. Inthe present embodiment, the wireless communication unit 402 is awireless module. The transmitter-side wireless module 402 is providedwith an antenna for wireless communication, and realizes short-rangewireless communication conforming to the IEEE 802.15 standard (Bluetooth(registered trademark)). The transmitter-side wireless module 402performs wireless communication with the flash 300 at predeterminedintervals, and notifies the transmitter microcomputer 401 of the timingat which the transmitter-side wireless module 402 received null data ornon-null data.

The transmitter-side wireless module 402 also includes thetransmitter-side interface 403, and transmits/receives data to/from thetransmitter microcomputer 401 via the transmitter-side interface 403.

Upon the transmitter 400 being attached to the accessory shoe (notshown) of the camera body 100, the transmitter-side interface 403 isconnected to the camera-side interface 112. As a result, the transmittermicrocomputer 401 can communicate with the camera microcomputer 101.

Next, with reference to FIGS. 8A and 8B, the following describes anoperation sequence of flash synchronization shooting in a case where thetransmitter 400 attached to the camera body 100 and the flash 300 areused as shown in FIG. 7A.

Note that, in the fifth embodiment, the configurations of the camera 10and the flash 300, and the operations of the camera body 100 performeduntil the second signal SW2 is turned ON are the same as those in thefirst embodiment.

The fifth embodiment is different from the first embodiment in that thecamera 10 and the flash 300 perform wireless communication via thetransmitter 400, and the transmitter-side wireless module 402 is usedinstead of the camera-side wireless module 111. In FIGS. 8A and 8B,communication performed using the transmitter 400 corresponds toprocessing performed in step S503 through which light emissioninformation is transmitted, processing performed in step S509 throughwhich a response is transmitted, and processing performed in step S519through which t3 is transmitted. Processing performed in these steps areadded to FIG. 3 according to the first embodiment. The fifth embodimentis otherwise the same as the first embodiment.

As described above, even in a case where the transmitter-side wirelessmodule 402, which is an external apparatus, is used instead of thecamera-side wireless module 111, it is possible to establishsynchronization between exposure performed by the camera 10 and lightemission performed by the flash 300.

Sixth Embodiment

The following describes a flash synchronization shooting systemaccording to a sixth embodiment.

FIG. 9 is a diagram showing an example of a flash synchronizationshooting system according to the sixth embodiment. When the camera 10and flashes 300A to 300C are set to a wireless communication mode,wireless communication is performed between the camera 10, whichoperates as a master, and the flashes 300A to 300C, which operate asslaves.

Although FIG. 9 shows three flashes 300A to 300C as flashes that performwireless communication with the camera 10, the number of flashes may betwo or four or more.

In the sixth embodiment, the configurations of the camera 10 and theflashes 300A to 300C and the wireless communication scheme employed bythe camera-side wireless module 111 and the flash-side wireless modules308 are the same as those shown in FIGS. 2A and 2B according to thefirst embodiment. The operations of the camera body 100 performed untilthe second signal SW2 is turned ON are the same as those according tothe first embodiment.

Next, with reference to FIGS. 10A and 10B, the following describes anoperation sequence of flash synchronization shooting in a case where thecamera 10 and the flashes 300A to 300C perform one-to-many communicationas shown in FIG. 9.

In step S600, the camera-side wireless module 111 and each of theflash-side wireless modules 308 of the flashes 300A to 300C performwireless communication at predetermined intervals (intervals a)asynchronously with the camera microcomputer 101 or the flashmicrocomputer 301. If there is no data to be transmitted, thecamera-side wireless module 111 and the flash-side wireless modules 308transmit/receive null data to/from each other. The camera-side wirelessmodule 111 and the flash-side wireless modules 308 respectively notifythe camera microcomputer 101 and the flash microcomputers 301 of thepoints in time at which the camera-side wireless module 111 and theflash-side wireless modules 308 received non-null data.

Upon the second signal SW2 being turned ON in step S601, the cameramicrocomputer 101 outputs, in step S602, light emission information,which contains, for example, information regarding the amount of lightto be emitted and the light emission mode of the flash 300A, to thecamera-side wireless module 111.

In step S603, upon the time to start wireless communication beingreached, the camera-side wireless module 111 transmits light emissioninformation to the flash-side wireless module 308 of the flash 300A.

In step S604, the flash-side wireless module 308 of the flash 300Aoutputs the light emission information received from the camera-sidewireless module 111 to the flash microcomputer 301. Also, the flashmicrocomputer 301 outputs a response to the light emission informationto the flash-side wireless module 308, and starts light emissionpreparation operations based on the light emission information.

In step S605, upon the time to start wireless communication beingreached, the camera-side wireless module 111 transmits light emissioninformation to the flash-side wireless module 308 of the flash 300B.

In step S606, the flash-side wireless module 308 of the flash 300Boutputs the light emission information received from the camera-sidewireless module 111 to the flash microcomputer 301. Also, the flashmicrocomputer 301 outputs a response to the light emission informationto the flash-side wireless module 308, and starts light emissionpreparation operations based on the light emission information.

In step S607, upon the time to start wireless communication beingreached, the camera-side wireless module 111 transmits light emissioninformation to the flash-side wireless module 308 of the flash 300C.

In step S608, the flash-side wireless module 308 of the flash 300Coutputs the light emission information received from the camera-sidewireless module 111 to the flash microcomputer 301. Also, the flashmicrocomputer 301 outputs a response to the light emission informationto the flash-side wireless module 308, and starts light emissionpreparation operations based on the light emission information.

In step S609, upon the time to start wireless communication beingreached, the flash-side wireless module 308 of the flash 300A transmitsa response to the camera-side wireless module 111.

In step S610, the camera-side wireless module 111 notifies the cameramicrocomputer 101 of the timing at which the camera-side wireless module111 received the response from the flash-side wireless module 308.

In step S611, after receiving the response notification from thecamera-side wireless module 111, the camera microcomputer 101 starts thetimer of the camera microcomputer 101. The camera microcomputer 101 alsoperforms control such as diaphragm driving control and mirror lifting upcontrol. Processing for control such as diaphragm driving control andmirror lifting up control, which varies depending on shootingconditions, is performed.

In step S612, upon the time to start wireless communication beingreached, the flash-side wireless module 308 of the flash 300B transmitsa response to the camera-side wireless module 111.

In step S613, the camera-side wireless module 111 notifies the cameramicrocomputer 101 of the timing at which the camera-side wireless module111 received the response from the flash-side wireless module 308.

In step S614, the camera microcomputer 101 acquires the value of thetimer, and calculates an interval tab between communication with theflash 300A and communication with the flash 300B.

In step S615, upon the time to start wireless communication beingreached, the flash-side wireless module 308 of the flash 300C transmitsa response to the camera-side wireless module 111.

In step S616, the camera-side wireless module 111 notifies the cameramicrocomputer 101 of the timing at which the camera-side wireless module111 received the response from the flash-side wireless module 308.

In step S617, the camera microcomputer 101 acquires the value of thetimer, and calculates an interval tbc between communication with theflash 300B and communication with the flash 300C.

In step S618, the camera microcomputer 101 calculates an interval tcabetween communication with the flash 300C and communication with theflash 300A by subtracting the sum of tab and tbc from the predeterminedcommunication interval α.

In step S619, the camera microcomputer 101 performs control such asdiaphragm driving control and mirror lifting up control. Upon completionof processing for control such as diaphragm driving control and mirrorlifting up control, which varies depending on shooting conditions, theremaining time to exposure is set to t0.

Upon the remaining time t0 to exposure being determined, the cameramicrocomputer 101 stops the timer in step S620, and acquires a timervalue β in step S621.

In step S622, the camera microcomputer 101 divides the period of time βacquired in step S621 by the predetermined communication interval α, andthe quotient thus obtained is the number of times wireless communicationwas performed during the period of time β, and the remainder is theperiod of time from when the last wireless communication with the flash300A was performed to when the timer was stopped. If this remainder isexpressed as t1, t1 is the period of time from when the wirelesscommunication was performed immediately before t0 was determined in stepS619, to when t0 was determined.

In the case where the camera microcomputer 101 performs wirelesscommunication with the flash 300A first, in step S623, the cameramicrocomputer 101 subtracts t1, obtained in step S622, from thepredetermined communication interval α, to obtain a period of time t2,which is a period of time from when t0 was determined to when thesubsequent wireless communication is to be performed.

In step S624, the camera microcomputer 101 subtracts t2, obtained instep S623, from the remaining time t0 to exposure, determined in stepS619, to obtain a period of time t3a remaining before the flash 300Aemits light.

In step S625, after determining t3a, the camera microcomputer 101subtracts tab, calculated in step S614, from t3a, to obtain a period oftime t3b remaining before the flash 300B emits light. Similarly, in stepS626, the camera microcomputer 101 subtracts tbc, calculated in stepS617, from t3b, to obtain a period of time t3c remaining before theflash 300C emits light.

In step S627, the camera microcomputer 101 outputs information regardingthe period of time t3a, t3b, and t3c calculated in steps S624 to S626,to the camera-side wireless module 111.

In step S628, upon the time to start wireless communication with theflash 300A being reached, the camera-side wireless module 111 transmitsinformation regarding the period of time t3a to the flash 300A.

The flash microcomputer 301 of the flash 300A sets t3a, received fromthe flash-side wireless module 308, as the period of waiting time.

In step S629, upon the time to start wireless communication with theflash 300B being reached, the camera-side wireless module 111 transmitsinformation regarding the period of time t3b to the flash 300B.

The flash microcomputer 301 of the flash 300B sets t3b, received fromthe flash-side wireless module 308, as the period of waiting time.

In step S630, upon the time to start wireless communication with theflash 300C being reached, the camera-side wireless module 111 transmitsinformation regarding the period of time t3c to the flash 300C.

The flash microcomputer 301 of the flash 300C sets t3c, received fromthe flash-side wireless module 308, as the period of waiting time.

In step S631, the camera microcomputer 101 performs exposure upon theperiod of time t0, i.e. t2+t3a, elapsing after step S620 has beencompleted.

In step S632, upon the periods of waiting time t3a, t3b, and t3c set insteps S628 to S630 elapsing, the flash microcomputers 301 of the flashes300A to 300C perform light emission based on information regarding thelight emission preparations performed in steps S604, S606, and S608,respectively.

Thus, the camera 10 and the flashes 300A to 300C synchronize with oneanother.

Upon the shooting sequence being complete in this way, the camera 10 andthe flashes 300A to 300C return to the shooting standby state in whichthe first signal SW1 is awaited.

Note that FIGS. 10A and 10B shows the case where the flash with whichthe camera 10 performs wireless communication first, after step S620 hasbeen completed, is the flash 300A. The following describes the casewhere the flash that communicates with the camera 10 first is the flash300B, and the case where that is the flash 300C, with reference to FIGS.11 and 12, respectively.

The flash with which the camera 10 performs wireless communication firstafter step S620 has been completed is changed depending on the value oft1. The relationship between the value of t1 and the flash with whichthe camera 10 communicates first is as follows.

0<t1≤tab:

the camera 10 communicates with the flash 300B first.

tab<t1≤tab+tbc:

the camera 10 communicates with the flash 300 first.

tab+tbc<t1≤α:

the camera 10 communicates with the flash 300A first.

With reference to FIG. 11, the following describes the case where thecamera 10 communicates with the flash 300B first, after step S620 hasbeen completed.

The steps up to step S621 in FIG. 11 are the same as those in FIGS. 10Aand 10B.

The value of t1 calculated in step S621 after the timer has been stoppedin step S620 satisfies (<t1≤tab. Therefore, it is determined that theflash with which the camera 10 performs wireless communication first isthe flash 300B. In step S633, the camera microcomputer 101 can obtainthe period of time t2 from when the timer was stopped in step S620 towhen the first wireless communication thereafter is to be performed, bysubtracting t1 from tab.

In step S634, the camera microcomputer 101 subtracts t2, obtained instep S633, from t0, obtained in step S619, to obtain the period of timet3b remaining before the flash 300B emits light, which is to betransmitted to the flash 300B.

In step S635, the camera microcomputer 101 subtracts tbc from t3b toobtain the period of time t3c remaining before light emission, which isto be transmitted to the flash 300C. Similarly, in step S636, the cameramicrocomputer 101 subtracts tca from t3c to obtain the period of timet3a remaining before light emission, which is to be transmitted to theflash 300A.

In step S637, the camera microcomputer 101 transmits informationregarding the period of time t3a to t3c, calculated in steps S634 toS636, to the camera-side wireless module 111.

In step S638, upon the time to start wireless communication with theflash 300B being reached, the camera-side wireless module 111 transmitsinformation regarding the period of time t3b to the flash 300B.

The flash microcomputer 301 of the flash 300B sets t3b, received fromthe flash-side wireless module 308, as the period of waiting time.

In step S639, upon the time to start wireless communication with theflash 300C being reached, the camera-side wireless module 111 transmitsinformation regarding the period of time t3c to the flash 300C.

The flash microcomputer 301 of the flash 300C sets t3c, received fromthe flash-side wireless module 308, as the period of waiting time.

In step S640, upon the time to start wireless communication with theflash 300A being reached, the camera-side wireless module 111 transmitsinformation regarding the period of time t3a to the flash 300A.

The flash microcomputer 301 of the flash 300A sets t3a, received fromthe flash-side wireless module 308, as the period of waiting time.

In step S641, the camera microcomputer 101 performs exposure upon theperiod of time t0, i.e. t2+t3b, elapsing after step S619 has beencompleted.

In step S642, upon the periods of waiting time t3a, t3b, and t3c set insteps S637 to S639 elapsing, the flash microcomputers 301 of the flashes300A to 300C perform light emission based on information regarding thelight emission preparations performed in steps S604, S606, and S608,respectively.

Thus, the camera 10 and the flashes 300A to 300C synchronize with oneanother.

Upon the shooting sequence being complete in this way, the camera 10 andthe flashes 300A to 300C return to the shooting standby state in whichthe first signal SW1 is awaited.

Subsequently, with reference to FIG. 12, the following describes thecase where the camera 10 communicates with the flash 300C first, afterstep S620 has been completed.

The value of t1 calculated in step S621 after the timer has been stoppedin step S620 satisfies tab<t1≤tab+tbc. Therefore, it is determined thatthe flash with which the camera 10 performs wireless communication firstis the flash 300C. In step S643, the camera microcomputer 101 can obtainthe period of time t2 from when the timer was stopped in step S620 towhen the first wireless communication thereafter is to be performed, bysubtracting t1 from tab+tbc.

In step S644, the camera microcomputer 101 subtracts t2, obtained instep S643, from t0, obtained in step S619, to obtain the period of timet3c remaining before light emission, which is to be transmitted to theflash 300C.

In step S645, the camera microcomputer 101 subtracts tca from t3c toobtain the period of time t3a remaining before light emission, which isto be transmitted to the flash 300A. Similarly, in step S646, the cameramicrocomputer 101 subtracts tab from t3a to obtain the period of timet3b remaining before light emission, which is to be transmitted to theflash 300B.

In step S647, the camera microcomputer 101 transmits informationregarding the period of time t3a to t3c, calculated in steps S644 toS646, to the camera-side wireless module 111.

In step S648, upon the time to start wireless communication with theflash 300C being reached, the camera-side wireless module 111 transmitsinformation regarding the period of time t3c to the flash 300C.

The flash microcomputer 301 of the flash 300C sets t3c, received fromthe flash-side wireless module 308, as the period of waiting time.

In step S649, upon the time to start wireless communication with theflash 300A being reached, the camera-side wireless module 111 transmitsinformation regarding the period of time t3a to the flash 300A.

The flash microcomputer 301 of the flash 300A sets t3a, received fromthe flash-side wireless module 308, as the period of waiting time.

In step S650, upon the time to start wireless communication with theflash 300B being reached, the camera-side wireless module 111 transmitsinformation regarding the period of time t3b to the flash 300B.

The flash microcomputer 301 of the flash 300B sets t3b, received fromthe flash-side wireless module 308, as the period of waiting time.

In step S651, the camera microcomputer 101 performs exposure upon theperiod of time t0, i.e. t2+t3c, elapsing after step S619 has beencompleted.

In step S652, upon the periods of waiting time t3a, t3b, and t3c set insteps S647 to S649 elapsing, the flash microcomputers 301 of the flashes300A to 300C perform light emission based on information regarding thelight emission preparations performed in steps S604, S606, and S608,respectively.

Thus, the camera 10 and the flashes 300A to 300C synchronize with oneanother.

Upon the shooting sequence being complete in this way, the camera 10 andthe flashes 300A to 300C return to the shooting standby state in whichthe first signal SW1 is awaited.

As described above, the camera microcomputer 101 acquires the points intime at which the camera microcomputer 101 received data from thecamera-side wireless module 111, and calculates the intervals betweencommunication with the plurality of flashes 300A to 300C (step S614,step S617, and step S618). As a result, the camera microcomputer 101 canfind out the timing of performing wireless communication with each ofthe plurality of flashes 300A to 300C at the time the remaining time toexposure is t0. Therefore, it is possible to obtain the order in whichcommunication with each of the plurality of flashes 300A to 300C is tobe performed, and individually calculate information regarding theperiods of time t3a to t3c remaining before the flashes 300A to 300Cemit light (steps S624 to S626). As a result, even in a case where thecamera 10 and the flashes 300A to 300C perform asynchronous wirelesscommunication, it is possible to establish synchronization between thetiming of exposure performed by the camera 10 and the timing of lightemission performed by each of the flashes 300A to 300C.

Note that even in a case where light metering and pre-flash emission forlight amount adjustment are respectively performed by the camera 10 andthe flashes 300A to 300C after the second signal SW2 has been turned ONin step S601, it is possible to establish synchronization between lightmetering performed by the camera 10 and pre-flash emission performed bythe flashes 300A to 300C, in the same manner as in the case of exposureperformed by the camera 10 and light emission performed by the flashes300A to 300C.

Seventh Embodiment

The following describes a flash synchronization shooting systemaccording to a seventh embodiment.

FIGS. 13A and 13B are diagrams illustrating an operation sequence offlash synchronization shooting in a case where the camera 10 and theflashes 300A to 300C perform one-to-many communication as shown in FIG.9.

The camera-side wireless module 111 according to the seventh embodimentnotifies the camera microcomputer 101 of the points in time at which thecamera-side wireless module 111 transmitted non-null data. Similarly,the flash-side wireless modules 308 of the flashes 300A to 300C notifythe flash microcomputers 301 of the points in time at which theflash-side wireless modules 308 received the non-null data,respectively.

Note that the configurations of the camera 10 and the flashes 300A to300C are the same as the configurations of those shown in FIGS. 2A and2B according to the first embodiment. Also, the wireless communicationscheme employed by the camera-side wireless module 111 and theflash-side wireless modules 308, and the operations of the camera body100 performed until the second signal SW2 is turned ON are the same asthose according to the first embodiment.

Although three flashes are used in the present embodiment, the number offlashes may be two or four or more.

Upon the second signal SW2 being turned ON in step S701, the cameramicrocomputer 101 outputs, in step S702, light emission information,which contains, for example, information regarding the amount of lightto be emitted and the light emission mode of the flash 300A, to thecamera-side wireless module 111.

In step S703, upon the time to start wireless communication beingreached, the camera-side wireless module 111 transmits light emissioninformation to the flash-side wireless module 308 of the flash 300A, andin step S704, the camera-side wireless module 111 outputs a transmissionnotification to the camera microcomputer 101.

In step S705, after receiving the transmission notification from thecamera-side wireless module 111, the camera microcomputer 101 starts thetimer of the camera microcomputer 101.

The flash-side wireless module 308 of the flash 300A outputs the lightemission information received from the camera-side wireless module 111to the flash microcomputer 301.

In step S706, the flash microcomputer 301 starts light emissionpreparation operations based on the light emission information.

In step S707, upon the time to start wireless communication beingreached, the camera-side wireless module 111 transmits light emissioninformation to the flash-side wireless module 308 of the flash 300B, andin step S708, the camera-side wireless module 111 transmits atransmission notification to the camera microcomputer 101.

In step S709, after receiving the transmission notification from thecamera-side wireless module 111, the camera microcomputer 101 acquiresthe timer value, and obtains the interval tab between communication withthe flash 300A and communication with the flash 300B.

The flash-side wireless module 308 of the flash 300B outputs the lightemission information received from the camera-side wireless module 111to the flash microcomputer 301.

In step S710, the flash microcomputer 301 starts light emissionpreparation operations based on the light emission information.

In step S711, upon the time to start wireless communication beingreached, the camera-side wireless module 111 transmits light emissioninformation to the flash-side wireless module 308 of the flash 300C, andin step S712, the camera-side wireless module 111 transmits atransmission notification to the camera microcomputer 101.

In step S713, after receiving the transmission notification from thecamera-side wireless module 111, the camera microcomputer 101 acquiresthe timer value, and obtains the interval tbc between communication withthe flash 300B and communication with the flash 300C.

The flash-side wireless module 308 of the flash 300C outputs the lightemission information received from the camera-side wireless module 111to the flash microcomputer 301.

In step S714, the flash microcomputer 301 starts light emissionpreparation operations based on the light emission information.

In step S715, the camera microcomputer 101 calculates the interval tcabetween communication with the flash 300C and communication with theflash 300A by subtracting the sum of tab and tbc from the predeterminedcommunication interval α.

Steps S716 to S729 are the same as steps S619 to S632 in FIGS. 10A and10B according to the sixth embodiment, and therefore descriptionsthereof are omitted. The method for determining the order in whichcommunication with each of the flashes 300A to 300C is to be performedafter the timer is stopped in step S717 is also the same as that shownin FIGS. 11 and 12 according to the sixth embodiment. Therefore, adescription thereof is omitted.

As described above, the camera microcomputer 101 acquires the points intime at which the camera microcomputer 101 received data from thecamera-side wireless module 111, and calculates the intervals betweencommunication with the plurality of flashes 300A to 300C (step S709,step S713, and step S715). As a result, the camera microcomputer 101 canfind out the timing of performing wireless communication with each ofthe plurality of flashes 300A to 300C at the time the remaining time toexposure is t0. Therefore, it is possible to obtain the order in whichcommunication with each of the plurality of flashes 300A to 300C is tobe performed, and individually calculate information regarding theperiods of time t3a to t3c remaining before the flashes 300A to 300Cemit light (steps S721 to S723). As a result, even when the camera 10and the flashes 300A to 300C perform asynchronous wirelesscommunication, it is possible to establish synchronization between thetiming of exposure performed by the camera 10 and the timing of lightemission performed by each of the flashes 300A to 300C.

Note that even in a case where light metering and pre-flash emission forlight amount adjustment are respectively performed by the camera 10 andthe flashes 300A to 300C after the second signal SW2 has been turned ONin step S601, it is possible to establish synchronization between lightmetering performed by the camera 10 and pre-flash emission performed bythe flashes 300A to 300C, in the same manner as in the case of exposureperformed by the camera 10 and light emission performed by the flashes300A to 300C.

Eighth Embodiment

The following describes a flash synchronization shooting systemaccording to an eighth embodiment.

FIGS. 14A and 14B are diagrams illustrating an operation sequence offlash synchronization shooting in a case where the camera 10 and theflashes 300A to 300C perform one-to-many communication as shown in FIG.9.

The camera-side wireless module 111 according to the eighth embodimentnotifies the camera microcomputer 101 of the points in time at which thecamera-side wireless module 111 transmitted data, which may be nulldata. Similarly, the flash-side wireless modules 308 of the flashes 300Ato 300C notify the flash microcomputers 301 of the points in time atwhich the flash-side wireless modules 308 received data, which may benull data, respectively.

Note that the configurations of the camera 10 and the flashes 300A to300C are the same as the configurations of those shown in FIGS. 2A and2B according to the first embodiment. Also, the wireless communicationscheme employed by the camera-side wireless module 111 and theflash-side wireless modules 308, and the operations of the camera body100 performed until the second signal SW2 is turned ON (step S800) arethe same as those according to the first embodiment.

Although three flashes are used in the present embodiment, the number offlashes may be two or four or more.

Steps S801 to S815 are the same as steps S701 to S715 in FIGS. 13A and13B according to the seventh embodiment, and therefore descriptionsthereof are omitted.

In step S816, the camera microcomputer 101 resets and starts the timerevery time the camera microcomputer 101 receives a communicationnotification from the flash 300A.

In step S817, the camera microcomputer 101 performs control such asdiaphragm driving control and mirror lifting up control. Upon completionof processing for control such as diaphragm driving control and mirrorlifting up control, which varies depending on shooting conditions, theremaining time to exposure is set to t0.

Upon the remaining time t0 to exposure being determined, the cameramicrocomputer 101 stops the timer in step S818, and acquires the timervalue. Then, in step S819, the camera microcomputer 101 sets the timervalue to t1, which is the period of time from when the wirelesscommunication was performed immediately before the remaining time t0 toexposure was determined, to when the remaining time t0 to exposure wasdetermined.

Steps S820 to S829 are the same as steps S623 to S632 in FIGS. 10A and10B according to the sixth embodiment. Also, the method for determiningthe order in which communication with each of the flashes 300A to 300Cis to be performed after the timer is stopped in step S818 is also thesame as that shown in FIGS. 11 and 12 according to the sixth embodiment.

As described above, the camera microcomputer 101 acquires the points intime at which the camera microcomputer 101 performed communication, fromthe camera-side wireless module 111, and calculates the intervalsbetween communication with the plurality of flashes 300A to 300C (stepS809, step S813, and step S815). As a result, the camera microcomputer101 can find out the timing of performing wireless communication witheach of the plurality of flashes 300A to 300C at the time the remainingtime to exposure is to. Therefore, it is possible to obtain the order inwhich communication with each of the plurality of flashes 300A to 300Cis to be performed, and individually calculate the periods of timeremaining before the flashes emit light (steps S821 to S823). As aresult, even when the camera 10 and the flashes 300A to 300C performasynchronous wireless communication, it is possible to establishsynchronization between the timing of exposure performed by the camera10 and the timing of light emission performed by each of the flashes300A to 300C.

Note that even in a case where light metering and pre-flash emission forlight amount adjustment are respectively performed by the camera 10 andthe flashes 300A to 300C after the second signal SW2 has been turned ONin step S801, it is possible to establish synchronization between lightmetering performed by the camera 10 and pre-flash emission performed bythe flashes 300A to 300C, in the same manner as in the case of exposureperformed by the camera 10 and light emission performed by the flashes300A to 300C.

Ninth Embodiment

The following describes a flash synchronization shooting systemaccording to a ninth embodiment.

FIGS. 15A and 15B are diagrams illustrating an operation sequence offlash synchronization shooting in a case where the camera 10 and theflashes 300A to 300C perform one-to-many communication as shown in FIG.9.

In the present embodiment, the camera 10 transmits, to the flashes 300Ato 300C, information that is required to calculate the periods of timeremaining before the flashes 300A to 300C emit light, and the flashes300A to 300C calculate the periods of time t3a to t3c, which are periodsof time from when the flashes 300A to 300C perform wirelesscommunication to when the flashes 300A to 300C emit light, respectively.

Note that, in the ninth embodiment, the configurations of the camera 10and the flashes 300A to 300C, the wireless communication scheme employedby the camera-side wireless module 111 and the flash-side wirelessmodules 308, and the operations of the camera body 100 performed untilthe second signal SW2 is turned ON are the same as those in the sixthembodiment.

Although three flashes are used in the present embodiment, the number offlashes may be two or four or more.

Steps S901 to S923 are the same as steps S601 to S623 in FIGS. 10A and10B according to the sixth embodiment, and therefore descriptionsthereof are omitted.

In step S924, the camera microcomputer 101 collects pieces of necessarydata for each of the flashes 300A to 300C according to the value of t1so that the flashes 300A to 300C can calculate the period of timeremaining before light emission, and outputs such data to thecamera-side wireless module 111. In FIGS. 15A and 15B, tab+tbc<t1≤α issatisfied. Therefore, t0 and t2 are to be transmitted to the flash 300A.How the flash with which the camera 10 performs wireless communicationfirst is changed depending on the value of t1 is as described withreference to FIGS. 11 and 12 according to the sixth embodiment.

In step S925, upon the time to start wireless communication with theflash 300A being reached, the camera-side wireless module 111 transmitsthe data received in step S924 to the flash 300A via the flash-sidewireless module 308.

The flash 300A calculates the period of time t3a remaining before theflash 300A emits light, based on t0 and t2 received in step S925, andsets t3a as the period of waiting time. It is possible to obtain t3a bysubtracting t2 from t0.

In step S926, upon the time to start wireless communication with theflash 300B being reached, the camera-side wireless module 111 transmitsthe data received in step S924 to the flash 300B via the flash-sidewireless module 308.

The flash 300B calculates the period of time t3b remaining before theflash 300B emits light, based on t0, t2, and tab received in step S926,and sets t3b as the period of waiting time. It is possible to obtain t3bby subtracting the sum of t2 and tab from t0.

In step S927, upon the time to start wireless communication with theflash 300C being reached, the camera-side wireless module 111 transmitsthe data received in step S924 to the flash 300C via the flash-sidewireless module 308.

The flash 300C calculates the period of time t3c remaining before theflash 300C emits light, based on t0, t2, tab, and tbc received in stepS927, and sets t3c as the period of waiting time. It is possible toobtain t3c by subtracting the sum of t2, tab, and tbc from t0.

The method for calculating the periods of time t3a to t3c remainingbefore the flashes 300A to 300C emit light, in the communication order,after the timer has been stopped in step S920, is as described withreference to FIGS. 11 and 12 according to the sixth embodiment.

In step S931, the camera microcomputer 101 performs exposure upon theperiod of time t0 elapsing after step S920 has been completed.

In step S932, upon the periods of waiting time t3a, t3b, and t3c set insteps S925 to S927 elapsing, the flash microcomputers 301 of the flashes300A to 300C perform light emission based on information regarding thelight emission preparations performed in steps S904, S906, and S908,respectively.

Thus, the camera 10 and the flashes 300A to 300C synchronize with oneanother.

Upon the shooting sequence being complete in this way, the camera 10 andthe flashes 300A to 300C return to the shooting standby state in whichthe first signal SW1 is awaited.

As described above, the camera microcomputer 101 transmits, to theflashes 300A to 300C, information that is required to calculate theperiods of time remaining before the flashes 300A to 300C emit light,and thus the flashes 300A to 300C can decide information regarding theperiods of time t3a to t3c, which are periods of time from when wirelesscommunication is performed to when the flashes 300A to 300C emit light,respectively. As a result, even when the camera 10 and the flashes 300Ato 300C perform asynchronous wireless communication, it is possible toestablish synchronization between the timing of exposure performed bythe camera 10 and the timing of light emission performed by each of theflashes 300A to 300C.

Note that even in a case where light metering and pre-flash emission forlight amount adjustment are respectively performed by the camera 10 andthe flashes 300A to 300C after the second signal SW2 has been turned ONin step S901, it is possible to establish synchronization between lightmetering performed by the camera 10 and pre-flash emission performed bythe flashes 300A to 300C, in the same manner as in the case of exposureperformed by the camera 10 and light emission performed by the flashes300A to 300C.

Tenth Embodiment

The following describes a flash synchronization shooting systemaccording to a tenth embodiment.

FIGS. 16A and 16B are diagrams illustrating an operation sequence offlash synchronization shooting in a case where the transmitter 400attached to the camera body 100 and the plurality of flashes 300A to300C are used as shown in FIG. 9.

Note that, in the tenth embodiment, the configurations of the camera 10and the flashes 300A to 300C, the wireless communication scheme employedby the camera-side wireless module 111 and the flash-side wirelessmodules 308, and the operations of the camera body 100 performed untilthe second signal SW2 is turned ON are the same as those in the sixthembodiment. Also, the configuration of the transmitter 400 is the sameas that in the fifth embodiment.

Although three flashes are used in the present embodiment, the number offlashes may be two or four or more.

The tenth embodiment is different from the sixth embodiment in that thecamera 10 and the flashes 300A to 300C perform wireless communicationvia the transmitter 400, and the transmitter-side wireless module 402 isused instead of the camera-side wireless module 111. In FIGS. 16A and16B, communication performed using the transmitter 400 corresponds toprocessing performed in step S1003 through which light emissioninformation is transmitted, processing performed in steps S1011, S1015,and S1019 through which a response is transmitted, and processingperformed in step S1032 through which t3a to t3c are transmitted.Processing performed in these steps are added to FIGS. 10A and 10Baccording to the sixth embodiment. The tenth embodiment is otherwise thesame as the sixth embodiment.

As described above, even in a case where the transmitter-side wirelessmodule 402, which is an external apparatus, is used instead of thecamera-side wireless module 111, it is possible to establishsynchronization between exposure performed by the camera 10 and lightemission performed by the flashes 300A to 300C.

Eleventh Embodiment

The following describes a flash synchronization shooting systemaccording to an eleventh embodiment.

FIG. 17 is a diagram illustrating an operation sequence of retryprocessing that is performed to re-transmit information at the time offlash synchronization shooting in a case where the camera 10 and theflash 300 perform one-to-one communication as shown in FIG. 1.

FIG. 17 illustrates an example in which, when transmission and receptionof time information t3 from the camera-side wireless module 111 to theflash-side wireless module 308 have failed in step S117 in FIG. 3, retryprocessing is performed to extend the remaining time t0 to exposure andre-transmit the information.

Note that, in the present embodiment, as in the above-describedembodiments, the camera 10 and the flash 300 perform wirelesscommunication at predetermined intervals (intervals a) (step S1100).Also, after transmitting the time information t3 to the flash 300, thecamera-side wireless module 111 notifies the camera microcomputer 101 ofthe point in time at which the camera-side wireless module 111 receiveda response (hereinafter referred to as a response packet (ACK)) from theflash 300. Similarly, the flash-side wireless module 308 notifies theflash microcomputer 301 of the point in time at which the flash-sidewireless module 308 received the time information t3 from the camera 10.

Note that the configurations of the camera 10 and the flash 300 are thesame as the configurations of those shown in FIGS. 2A and 2B accordingto the first embodiment. Also, the wireless communication schemeemployed by the camera-side wireless module 111 and the flash-sidewireless module 308, and operations of the camera body 100 that areperformed until the second signal SW2 is turned ON are the same as thoseaccording to the first embodiment. Also, processing steps (steps S1102and S1103) that are performed in the camera body 100 from when thesecond signal SW2 is turned ON (step S1101) to when the remaining timet0 to exposure is determined are the same as those in the firstembodiment.

In step S1104, the camera microcomputer 101 outputs the time informationt3 calculated in step S115 in FIG. 3, to the camera-side wireless module111.

In step S1105, upon the time to start wireless communication beingreached, the camera-side wireless module 111 transmits the timeinformation t3 to the flash-side wireless module 308. In the presentembodiment, it is assumed that the camera-side wireless module 111 hasfailed to transmit t3 to the flash-side wireless module 308. If thecamera-side wireless module 111 does not receive a response packet fromthe flash-side wireless module 308 within a predetermined period oftime, the camera-side wireless module 111 determines that thetransmission of t3 has failed, and outputs a failure notification to thecamera microcomputer 101 in step S1106.

In step S1107, upon receiving the failure notification, the cameramicrocomputer 101 performs processing to extend the remaining time t0 toexposure, to extend the remaining time t0 to exposure to t0+α as shownin step S1108, in order to perform retry processing.

In step S1109, upon the time to start the subsequent wirelesscommunication being reached, the camera-side wireless module 111re-transmits the time information t3 to the flash-side wireless module308.

In step S1110, the flash-side wireless module 308 outputs the timeinformation t3 received from the camera-side wireless module 111, to theflash microcomputer 301 as light emission information.

In step S1111, the flash-side wireless module 308 transmits a responsepacket indicating that the flash-side wireless module 308 has receivednon-null data from the camera-side wireless module 111, to thecamera-side wireless module 111.

In step S1112, the flash microcomputer 301 sets t3, received from theflash-side wireless module 308, as the period of waiting time, and uponthe period of time t3 elapsing, the flash microcomputer 301 performslight emission based on information regarding the light emissionpreparations performed in step S106 shown in FIG. 3.

In step S1113, the camera microcomputer 101 performs exposure upon aperiod of time t0+α elapsing from step S1103. As a result, the camera 10and flash 300 synchronize with each other.

Upon the shooting sequence being completed in this way, the cameramicrocomputer 101 and the flash microcomputer 301 return to the shootingstandby state.

Next, with reference to FIG. 18, the following describes an operationsequence that is performed in a case where, after transmitting the timeinformation t3 to the flash 300, the camera 10 has failed to receive aresponse packet from the flash 300.

FIG. 18 is a diagram illustrating an operation sequence of retryprocessing that is performed to re-transmit information at the time offlash synchronization shooting in a case where the camera 10 and theflash 300 perform one-to-one communication as shown in FIG. 1.

FIG. 18 illustrates an example in which retry processing is performed ina case where the camera-side wireless module 111 does not receive aresponse packet from the flash-side wireless module 308 aftertransmitting the time information t3 to the flash-side wireless module308 in step S117 shown in FIG. 3.

Note that the configurations of the camera 10 and the flash 300 are thesame as the configurations of those shown in FIGS. 2A and 2B accordingto the first embodiment. Also, the wireless communication schemeemployed by the camera-side wireless module 111 and the flash-sidewireless module 308, and operations that are performed until the secondsignal SW2 of the camera body 100 is turned ON are the same as thoseaccording to the first embodiment. Also, the camera 10 and the flash 300perform communication at predetermined communication intervals a (stepS1200). Also, processing steps (steps S1202 to S1206) that are performedin the camera body 100 from when the second signal SW2 is turned ON(step S1201) to when the remaining time t0 to exposure is determined andthe time information t3 is transmitted are the same as those in thefirst embodiment.

In step S1205, upon the time to start wireless communication beingreached, the camera-side wireless module 111 transmits the timeinformation t3 to the flash-side wireless module 308. Here, it isassumed that the camera-side wireless module 111 has failed to receive aresponse packet from the flash-side wireless module 308 (step S1207)after transmitting t3 to the flash-side wireless module 308. If thecamera-side wireless module 111 does not receive a response packet fromthe flash-side wireless module 308 within a predetermined period oftime, the camera-side wireless module 111 determines that the receptionof a response packet has failed, and outputs a failure notification tothe camera microcomputer 101 in step S1208.

Processing performed in steps S1209 to S1213 is the same as thatperformed in steps S1107 to S1111 shown in FIG. 17.

In step S1214, after receiving the time information t3 in step S1212,the flash microcomputer 301 cancels t3 set in step S1206 as the periodof waiting time, and sets t3 received in step S1212 as the period ofwaiting time again. Then, upon t3 elapsing, the flash microcomputer 301emits light based on information regarding the light emissionpreparation operations performed in step S106 shown in FIG. 3.

In step S1215, the camera microcomputer 101 performs exposure upon aperiod of time t0+α elapsing from step S1203. As a result, the camera 10and flash 300 synchronize with each other.

Upon the shooting sequence being completed in this way, the cameramicrocomputer 101 and the flash microcomputer 301 return to the shootingstandby state.

Thus, if the camera-side wireless module 111 does not receive a responsepacket from the flash-side wireless module 308 in response to the lightemission information that the camera-side wireless module 111 hastransmitted to the flash-side wireless module 308, the camera-sidewireless module 111 notifies the camera microcomputer 101 of the failurein receiving a response packet. Upon being notified by the camera-sidewireless module 111 of the failure in receiving a response packet, thecamera microcomputer 101 extends the remaining time t0 to exposure bythe predetermined communication interval α, so that time information canbe re-transmitted. To realize retry processing, a condition that theremaining time t0 to exposure is greater than twice the predeterminedcommunication interval α (t0>2α) is provided. That is, the conditionallows communication between the camera 10 and the flash 300 to beperformed twice or more during the remaining time to exposure.

Also, there is the possibility of operability for the user beingaffected by retry processing if retry processing is repeated more thanonce, and therefore an upper limit is set for the number of times retryprocessing can be performed. It is assumed that, if the camera-sidewireless module 111 does not receive a response packet through retryprocessing before the upper limit of the number of times is reached, theretry processing is stopped and the camera microcomputer 101 transitionsto a shooting sequence.

In the present embodiment, a failure notification, which indicates thatthe camera-side wireless module 111 has failed to receive a responsepacket, triggers the camera microcomputer 101 to extend the remainingtime t0 to exposure. However, the reception of a response packet maytrigger the camera microcomputer 101. For example, after the remainingtime t0 to exposure has been confirmed (steps S1103 and S1203), thecamera microcomputer 101 enters a waiting state. The camera-sidewireless module 111 sets t0 to light emission information that is to betransmitted to the flash-side wireless module 308, and after receiving aresponse packet corresponding to the light emission information, thecamera-side wireless module 111 outputs a reception notification to thecamera microcomputer 101. The camera microcomputer 101 performs exposureupon t0 elapsing after the camera microcomputer 101 receives thereception notification. As a result, the camera 10 and flash 300synchronize with each other.

If the remaining time t0 to exposure is long enough and the flash 300can emit light before when exposure is to be performed even if retryprocessing is performed more than once, it is unnecessary to extend theremaining time to exposure. Whether or not the camera 10 performs retryprocessing or extends the remaining time t0 to exposure may be decidedbased on conditions such as the shutter speed.

Twelfth Embodiment

The following describes a flash synchronization shooting systemaccording to a twelfth embodiment.

FIG. 19 is a diagram illustrating an operation sequence of retryprocessing that is performed to re-transmit information at the time offlash synchronization shooting using the transmitter 400 attached to thecamera body 100 and the flash 300 as shown in FIG. 7A.

FIG. 19 illustrates an example in which, when transmission and receptionof time information t3 from the transmitter-side wireless module 402 tothe flash-side wireless module 308 have failed in step S520 in FIG. 8B,retry processing is performed to extend the remaining time t0 toexposure and re-transmit the information.

Note that, in the twelfth embodiment, the configurations of the camera10 and the flash 300, and the operations of the camera body 100performed until the second signal SW2 is turned ON are the same as thosein the first embodiment.

The twelfth embodiment is different from the eleventh embodiment in thatthe camera 10 and the flash 300 perform wireless communication via thetransmitter 400, and the transmitter-side wireless module 402 is usedinstead of the camera-side wireless module 111. Communication that usesthe transmitter 400 is performed to transmit light emission informationin steps S1304 and S1305 and a failure notification in step S1307 andS1308 in FIG. 19. Processing performed in these steps is added to FIG.17 according to the eleventh embodiment. The twelfth embodiment isotherwise the same as the eleventh embodiment.

As described above, even in a case where the transmitter-side wirelessmodule 402, which is an external apparatus, is used instead of thecamera-side wireless module 111, it is possible to perform retryprocessing and establish synchronization between exposure performed bythe camera 10 and light emission performed by the flash 300.

In the twelfth embodiment, retry processing may be performed in a casewhere the camera 10 fails to receive a response packet from the flash300 after transmitting time information t3 to the flash 300, as in FIG.18 according to the eleventh embodiment.

Thirteenth Embodiment

The following describes a flash synchronization shooting systemaccording to a thirteenth embodiment.

FIGS. 20A and 20B are diagrams illustrating an operation sequence ofretry processing that is performed to re-transmit information at thetime of flash synchronization shooting in a case where the camera 10 andthe flashes 300A to 300C perform one-to-many communication as shown inFIG. 9.

FIGS. 20A and 20B illustrate an example in which, when transmission oftime information t3c from the camera-side wireless module 111 to theflash-side wireless module 308 of the flash 300C has failed in step S630in FIG. 10B, retry processing is performed to extend the remaining timet0 to exposure and re-transmit the information.

Note that, in the present embodiment, as in the above-describedembodiments, the camera 10 and each of the flashes 300A to 300C performwireless communication at predetermined intervals (intervals a) (stepS1400). Also, after transmitting the pieces of time information t3a tot3c to the flash-side wireless modules 308 of the flashes 300A to 300C,the camera-side wireless module 111 notifies the camera microcomputer101 of the points in time at which the camera-side wireless module 111received response packets from the flashes 300A to 300C. Similarly, theflash-side wireless modules 308 of the flashes 300A to 300C notify theflash microcomputers 301 of the points in time at which the flash-sidewireless modules 308 received the pieces of time information t3a to t3cfrom the camera 10.

Note that the configurations of the camera 10 and each of the flashes300A to 300C are the same as the configurations of those shown in FIGS.2A and 2B according to the first embodiment. Also, the wirelesscommunication scheme employed by the camera-side wireless module 111 andthe flash-side wireless modules 308, and operations that are performedby the camera body 100 until the second signal SW2 is turned ON are thesame as those according to the first embodiment. Also, the camera 10 andthe flashes 300A to 300C perform communication at predeterminedcommunication intervals a (step S1400). Also, processing steps (stepsS1402 to S1408) that are performed from when the second signal SW2 ofthe camera body 100 is turned ON (step S1401) to when the remaining timet0 to exposure is determined and the time information t3 is transmittedare the same as those in the sixth embodiment.

Although three flashes are used in the present embodiment, the number offlashes may be two or four or more.

In steps S1405, S1407, and S1409, upon the time to perform wirelesscommunication being reached, the camera-side wireless module 111transmits the pieces of time information t3a to t3c to the flash-sidewireless modules 308 of the flashes 300A to 300C. Here, it is assumedthat the camera-side wireless module 111 has failed to receive aresponse packet from the flash-side wireless module 308 of the flash300C (step S1409). If the camera-side wireless module 111 does notreceive a response packet from the flash-side wireless module 308 of theflash 300C within a predetermined period of time, the camera-sidewireless module 111 determines that the reception of a response packethas failed, and outputs a failure notification to the cameramicrocomputer 101 in step S1410.

In step S11411, upon receiving the failure notification, the cameramicrocomputer 101 performs processing to extend the remaining time t0 toexposure, to extend the remaining time t0 to exposure to t0+α as shownin step S1412, in order to perform retry processing.

In steps S1413, S1415, and S1417, upon the time to perform thesubsequent wireless communication being reached, the camera-sidewireless module 111 re-transmits the pieces of time information t3a tot3c to the flash-side wireless modules 308 of the flashes 300A to 300C.The flash-side wireless modules 308 of the flashes 300A to 300C outputthe pieces of time information t3a to t3c received from the camera-sidewireless module 111, to the flash microcomputers 301 of the flashes 300Ato 300C as pieces of light emission information.

In steps S1414 and S1416, the flash-side wireless modules 308 of theflashes 300A and 300B transmit response packets indicating that theflash-side wireless modules 308 have received non-null data from thecamera-side wireless module 111, to the camera-side wireless module 111.

In step S1419, the flash microcomputers 301 of the flashes 300A and 300Bcancel t3a and t3b received in steps S1415 and S1417 and set as theperiods of waiting time in steps S1406 and S1408. The flashmicrocomputers 301 also set the pieces of time information t3a and t3breceived in steps S1413 and S1415 again, as the periods of waiting time.The flash microcomputer 301 of the flash 300C did not receive timeinformation t3c in step S1409, and t3c has not been set as the period ofwaiting time. Therefore, the time information t3c received in step S1417is newly set as the period of waiting time. Then, upon the periods t3ato t3c elapsing, the flash microcomputers 301 respectively emit lightbased on information regarding the light emission preparation operationsperformed in steps S604, S606, and S608 shown in FIG. 10A.

In step S1420, the camera microcomputer 101 performs exposure upon aperiod of time t0+α elapsing from step S1403. As a result, the camera 10and flashes 300A to 300C synchronize with each other.

Upon the shooting sequence being completed in this way, the cameramicrocomputer 101 and the flash microcomputers 301 of the flashes 300Ato 300C return to the shooting standby state.

Thus, if the camera-side wireless module 111 does not receive a responsepacket from at least one flash in response to the pieces of lightemission information that the camera-side wireless module 111 hastransmitted to the flashes 300A to 300C, the camera-side wireless module111 notifies the camera microcomputer 101 of the failure in receiving aresponse packet. Upon being notified by the camera-side wireless module111 of the failure in receiving a response packet, the cameramicrocomputer 101 extends the remaining time t0 to exposure by thepredetermined communication interval α, so that time information can bere-transmitted.

Note that descriptions of a condition for allowing retry processing tobe performed, the upper limit of the number of times retry processingcan be performed, and a condition for extending the remaining time toexposure (i.e. descriptions of the fact that reception of a responsepacket may be a trigger, and a case in which the remaining time toexposure is long enough) are omitted because they are the same as in theeleventh embodiment.

In the thirteenth embodiment, retry processing may be performed in acase where the camera 10 fails to receive a response packet from theflashes 300A to 300C after transmitting the pieces of time informationt3a to t3c to the flashes 300A to 300C, as in FIG. 18 according to theeleventh embodiment.

Also, the flashes 300A to 300C according to the thirteenth embodimentmay perform communication with the camera 10 via the transmitter 400 asin the tenth and twelfth embodiment.

Other Embodiment

Embodiment(s) of the present invention can also be realized by acomputer of a system or apparatus that reads out and executes computerexecutable instructions (e.g., one or more programs) recorded on astorage medium (which may also be referred to more fully as a‘non-transitory computer-readable storage medium’) to perform thefunctions of one or more of the above-described embodiment(s) and/orthat includes one or more circuits (e.g., application specificintegrated circuit (ASIC)) for performing the functions of one or moreof the above-described embodiment(s), and by a method performed by thecomputer of the system or apparatus by, for example, reading out andexecuting the computer executable instructions from the storage mediumto perform the functions of one or more of the above-describedembodiment(s) and/or controlling the one or more circuits to perform thefunctions of one or more of the above-described embodiment(s). Thecomputer may comprise one or more processors (e.g., central processingunit (CPU), micro processing unit (MPU)) and may include a network ofseparate computers or separate processors to read out and execute thecomputer executable instructions. The computer executable instructionsmay be provided to the computer, for example, from a network or thestorage medium. The storage medium may include, for example, one or moreof a hard disk, a random-access memory (RAM), a read only memory (ROM),a storage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2017-206331, filed Oct. 25, 2017 which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. An image capturing apparatus that controls alight emitting apparatus, comprising: a wireless communication unitconfigured to perform communication with the light emitting apparatus atpredetermined intervals; a deciding unit configured to, upon receivingan instruction to cause the light emitting apparatus to emit light toperform shooting, decide information regarding a period of timeremaining before the light emitting apparatus emits light, based on theremaining time to exposure and a period of time from when the remainingtime starts decreasing, to when the wireless communication unit performsa first wireless communication thereafter; and a control unit configuredto perform control so that the information regarding the period of timedecided by the deciding unit is transmitted to the light emittingapparatus through the first wireless communication with the lightemitting apparatus, wherein, in a case where transmission and receptionof the information regarding the period of time between the imagecapturing apparatus and the light emitting apparatus fail, the controlunit performs control so that the information regarding the period oftime is re-transmitted.
 2. The apparatus according to claim 1, whereinin a case where the wireless communication unit does not receive aresponse from the light emitting apparatus after transmitting theinformation regarding the period of time, the control unit determinesthat transmission and reception of the information regarding the periodof time have failed.
 3. The apparatus according to claim 1, wherein in acase where transmission and reception of the information regarding theperiod of time fail, the wireless communication unit notifies thecontrol unit of the failure.
 4. The apparatus according to claim 3,wherein in a case where the control unit is notified by the wirelesscommunication unit of the failure, the control unit extends theremaining time to exposure by adding the predetermined interval to theremaining time to exposure, and the information regarding the period oftime is re-transmitted.
 5. The apparatus according to claim 4, whereinin a case where re-transmission can be performed within the remainingtime to exposure, the information regarding the period of time isre-transmitted without the control unit extending the remaining time toexposure.
 6. The apparatus according to claim 1, wherein the remainingtime to exposure is longer than twice the predetermined interval.
 7. Theapparatus according to claim 1, wherein the number of times there-transmission can be performed has an upper limit, and in a case wherethe information regarding the period of time cannot be transmitted orreceived through the re-transmission before the upper limit is reached,the control unit performs control to stop the re-transmission and make atransition to a shooting operation.
 8. The apparatus according to claim1, wherein the light emitting apparatus is provided in a plurality, andthe wireless communication unit is capable of communicating with theplurality of light emitting apparatuses, and the control unit performscontrol so that the information regarding the period of time istransmitted to the plurality of light emitting apparatuses, and in acase where transmission and reception of the information regarding theperiod of time fails for at least one of the plurality of light emittingapparatuses, the control unit performs control so that the informationregarding the period of time is re-transmitted to all of the lightemitting apparatuses.
 9. The apparatus according to claim 1, wherein thewireless communication unit is attachable to the image capturingapparatus.
 10. A light emitting apparatus that is controlled by an imagecapturing apparatus, comprising: a wireless communication unitconfigured to perform communication with the image capturing apparatusat predetermined intervals; and a deciding unit configured to, afterreceiving light emission information that is used to perform lightemission preparations from the image capturing apparatus, receive timeinformation regarding a period of time from when remaining time beforethe image capturing apparatus performs exposure starts decreasing, towhen the wireless communication unit performs a first wirelesscommunication thereafter, and obtain a period of waiting time remainingbefore the light emitting apparatus emits light, based on theinformation regarding the period of time, wherein, in a case where thedeciding unit receives new time information after receiving the timeinformation from the image capturing apparatus, the deciding unitcancels the period of waiting time decided based on the previouslyreceived time information, and decides a period of waiting time based onthe newly received time information.
 11. The apparatus according toclaim 10, wherein in a case where the time information is received fromthe image capturing apparatus, the wireless communication unit transmitsa response to the image capturing apparatus.
 12. The apparatus accordingto claim 10, wherein the light emitting apparatus is provided inplurality and each of the light emitting apparatuses is capable ofcommunicating with the image capturing apparatus, and each of the lightemitting apparatuses obtains the period of waiting time based on thetime information received from the image capturing apparatus.
 13. Amethod for controlling an image capturing apparatus that includes awireless communication unit configured to communicate with a lightemitting apparatus at predetermined intervals, and controls the lightemitting apparatus via wireless communication, the method comprising:upon receiving an instruction to cause the light emitting apparatus toemit light to perform shooting, deciding time information regarding aperiod of time remaining before the light emitting apparatus emitslight, based on the remaining time to exposure and a period of time fromwhen the remaining time starts decreasing to when the image capturingapparatus performs the first wireless communication thereafter; andcontrolling such that the time information regarding the decided periodof time is transmitted to the light emitting apparatus through the firstwireless communication with the light emitting apparatus, wherein, inthe controlling, in a case where transmission and reception of the timeinformation between the image capturing apparatus and the light emittingapparatus fail, the control unit performs control so that the timeinformation is re-transmitted.
 14. A method for controlling a lightemitting apparatus that includes a wireless communication unitconfigured to communicate with an image capturing apparatus atpredetermined intervals, and is controlled by the image capturingapparatus via wireless communication, the method comprising: afterreceiving light emission information that is used to perform lightemission preparations from the image capturing apparatus, receiving timeinformation regarding a period of time from when remaining time beforethe image capturing apparatus performs exposure starts decreasing, towhen the first wireless communication thereafter is to be performed, andobtaining a period of waiting time remaining before the light emittingapparatus emits light, based on the information regarding the period oftime, wherein, in the obtaining, in a case where new time information isreceived after the time information has been received from the imagecapturing apparatus, the period of waiting time decided based on thepreviously received time information is cancelled, and a period ofwaiting time is decided based on the newly received time information.15. A non-transitory computer-readable storage medium storing a programfor causing a computer to execute a method for controlling an imagecapturing apparatus that includes a wireless communication unitconfigured to communicate with a light emitting apparatus atpredetermined intervals, and controls the light emitting apparatus viawireless communication, the method comprising: upon receiving aninstruction to cause the light emitting apparatus to emit light toperform shooting, deciding time information regarding a period of timeremaining before the light emitting apparatus emits light, based on theremaining time to exposure and a period of time from when the remainingtime starts decreasing to when the image capturing apparatus performsthe first wireless communication thereafter; and controlling such thatthe time information regarding the decided period of time is transmittedto the light emitting apparatus through the first wireless communicationwith the light emitting apparatus, wherein, in the controlling, in acase where transmission and reception of the time information betweenthe image capturing apparatus and the light emitting apparatus fail, thecontrol unit performs control so that the time information isre-transmitted.
 16. A non-transitory computer-readable storage mediumstoring a program for causing a computer to execute a method forcontrolling a light emitting apparatus that includes a wirelesscommunication unit configured to communicate with an image capturingapparatus at predetermined intervals, and is controlled by the imagecapturing apparatus via wireless communication, the method comprising:after receiving light emission information that is used to perform lightemission preparations from the image capturing apparatus, receiving timeinformation regarding a period of time from when remaining time beforethe image capturing apparatus performs exposure starts decreasing, towhen the first wireless communication thereafter is to be performed, andobtaining a period of waiting time remaining before the light emittingapparatus emits light, based on the information regarding the period oftime, wherein, in the obtaining, in a case where new time information isreceived after the time information has been received from the imagecapturing apparatus, the period of waiting time decided based on thepreviously received time information is cancelled, and a period ofwaiting time is decided based on the newly received time information.